Since RVGL 18.1110a or RVGL 18.1112a the ESC-, as well the Arrow-Keys are not working anymore in the multiplayer lobby, as soon the race have started (accessible via TAB key). This makes it also impossible for a host to check the players cars, put specific players to spec mode, or remove players from the lobby.

Edit: This also means, that exiting a multiplayer game is not possible anymore. As a workaround, I quit a mutliplayergame by using F11 and X at the moment.